Field of the Invention
The present invention relates to a pipe structure, and an aircraft including the pipe structure.
Description of the Related Art
An airframe of aircraft is provided with a pipe through which high-temperature bleed air from an engine flows.
For the purpose of weight saving of aircraft, the bleed air pipe is formed to be relatively thin-walled. Thus, there is a possibility that a leak of the bleed air occurs with cracks or corrosion being caused when the bleed air pipe is used over a long period of time.
In order to detect the leak from the bleed air pipe, an arrangement has been proposed which detects a leak by transmitting high-frequency radiation coupled to a bleed air pipe from a transmitting device to cause the high-frequency radiation to propagate along the bleed air pipe, receiving radiation propagating to the outside from a crack or the like of the bleed air pipe, and performing evaluation (National Publication of International Patent Application No. 2009-511884).
In order to detect the leak from the bleed air pipe, a plurality of vent holes from which the leaking bleed air flows out to the outside are formed in a cover that covers the bleed air pipe at intervals in a length direction of the pipe. A line-shaped sensor whose temperature is increased by the bleed air flowing out from the vent holes is provided so as to sequentially pass by the vent holes. The leak can be detected based on electrical resistance of the sensor that is changed when the temperature is increased.
The bleed air pipe and the sensor are arranged in a narrow space that is prepared within a main wing or a fuselage, and are mounted to a peripheral member by a bracket.
Positions of the vent holes from which the high-temperature bleed air flows out during the leak are set by avoiding a position facing a member that is susceptible to heat. However, if a leak with a small flow rate in an initial stage of cracks or corrosion is not detected, and the leak is detected only after the flow rate of the bleed air flowing out from the vent hole is increased with the progress of the cracks or the corrosion, heat generated by the leak of the bleed air affects a larger area.
In accordance with the arrangement for detecting a leak in JP 2009-511884 A, the leak can be quickly detected. However, since the transmitting device/a receiving device of the high-frequency radiation, and an evaluation device are required, a cost of the arrangement is high. Particularly, it is not easy to construct an algorithm for appropriately evaluating the received high-frequency radiation and determining the occurrence of the leak. Thus, the arrangement cost is increased.
Thus, an object of the present invention is to provide a pipe structure that can reliably detect even a leak with a small flow rate corresponding to a defect in an initial stage of a pipe by using a line-shaped sensor without using an expensive device, and an aircraft including the pipe structure.